SEALED METALLIC CABINET SET UP BY SYMMETRICAL PROFILE ELEMENTS, AND PROCESS FOR THE CONSTRUCTION OF THE PROFILE ELEMENTS

Abstract: Sealed metallic cabinet to contain electric and electronic equipment comprising a framework set up by a plurality of interlocked profile frame sections on which external side panels (4, 5, 6, 7, 8) and at least one door (9) are installed, provided with sealing gaskets (32). The profile frame sections comprise two perpendicular external side sections (13, 14) of the same length and two internal side sections (11, 12) setting up a square space (10) together with the external side sections (13, 14). The profile is symmetrical with respect to the diagonal plane (P) passing through the intersection corner of the planes containing said external side sections (13, 14). Two or more cabinets can be joined to set up a single structure by means of M-shaped flanges (40) and sealing gaskets (50).

Description: Sealed metallic cabinet set up by symmetrical profile elements,and process for the construction of the profile elements Technical Field This invention relates to a metallic sealing cabinet to contain electric and electronic equipment such as for example telecommunication apparatus or switch boards, control boards etc. More precisely the invention relates to cabinets of the above-mentioned type realized with symmetrical frame sections, to the structures obtained by connecting two or more of such cabinets, as well as to a process for the construction of such symmetrical frame sections. The case set up by the cabinet as a whole has to guarantee the protection of the contained elements from external environmental influence. The degree, of protection of cabinets of this type is internationally codified by IEC (International European Community) standards by two numbers for example by the mark IP 55. The first number indicates the degree of penetration of external objects while the second one indicates the penetration of liquids, generally water, and it varies between 0 and 6 passing from vertical dripping to the inclined one, to sprinkling, to jets and finally to complete immersion. Background Art The Italian utility model application No. 22023 B/90 describes a sealing cabinet for electric equipment the framework of which is set up by frame sections with an open asymmetrical configuration (or which boundary edges of the origin sheet metal do not touch each other) providing for two perpendicularly arranged limbs which are connected by a plurality of right angle connection segments with the boundary edges of the limbs penetrating in gaskets. This section is not symmetrical and comprises limitations on the side sections suitable to receive a door or an openable panel provided with hinges. Said limitations are inherent by the fact that due to the so-called asymmetry the front and side edges of the frame sections are not of the same dimensions so that it is difficult to apply hinge elements on one or the other edge unless using two different types of hinge elements the first of which for example to be matchable at the front edge while the other type is for example matchable at the side edge. In other words when using an asymmetrical section it is only possible to assure a perfect interchangeability of fixed and openable panels on all side sections of the cabinet by using two different types of hinge elements. The European patent N. 144 955 describes a framework for an electric switchboard cabinet set up by twelve elements realized with a unique section type which cross section is tetragonal provided with a closed longitudinal hollow, and which provides for two internal side edges which extend perpendicularly to each other setting up a corner. One of the edges ends up in a refolding of the sheet metal forming a sealing web while the other end edge provides for a contact web and has a flange extending parallel to the side of the cabinet. Therefore the section is not symmetrical and this involves (also with reference to the section of the above-mentioned utility model application) two different moment of inertia values compared to the axes X and Y in the cross section plane of the profile. As a consequence of the above-mentioned different values in case of bending and torsion stress there is unbalanced stress acting on the profile, so that its parts are stressed in a non uniform way. Moreover the asymmetrical profile which main advantage is that of setting up a flange extending parallel to the side of the cabinet which is used in order to couple two cabinets together, involves a complex and expensive profile forming operation and needs additional elements such as a threaded coupling and further holes in the profile to introduce through those a tool to tighten the screws in the coupling and other holes in the webs to make the screws pass through. Analogously to what previously reported with reference to the utility model application no. 22033 B/90, the asymmetry created by the above-mentioned flange introduces an additional limitation consisting in the impossibility to assure a perfect interchangeability of the fixed and openable panels on all side sections of the cabinet. Objects of the Invention The objects of the present invention is to overcome the limitations and inconveniences of the prior art described before and in particular to realize a symmetrical section configuration without any difference between contact and sealing web, and thus easy to be produced at low costs allowing at the same time the sealed connection of two or more cabinets by means of the simple additional element. Disclosure of the Invention The invention achieves these objects by a sealed metallic cabinet, especially for electric and electronic equipment comprising a framework set up by twelve interconnected frame sections of the same profile on which external panels and doors are installed provided with sealing gaskets, the cross section of the frame sections comprising a first and a second external side sections which extend substantially in a perpendicular way to each other, and a first and a second internal side sections which extend substantially in a perpendicular way to each other, said first and second external side sections being connected to said first and second internal side sections by means of a first and a second connecting portions, the combination of said side sections setting up a square space inside the frame sections, characterized in that: - said profile is symmetrical with respect to the diagonal plane passing through the intersection angle of the plane containing said external side sections; - the ends edges of said first and second connecting portions forming, in cooperation with the ends edges of a said first and second internal side, sealing struts able to engage said sealing gaskets of said external panels and door. Moreover the invention consists in a structure, especially for electric and electronic equipment, comprising two or more metallic cabinets which are arranged in an adjacent and connected way, characterized in that between two parallel and opposite frame sections belonging to two adjacent frameworks a flange with an open M section is put, the legs of said flange provided with holes being abutted respectively on the external side sections of the symmetrical profiles of the two frame sections, said flange being fixed to blind threaded bushes applied to said external side sections by means of screws passing through holes of the flange, and further characterized in that a sealing gasket is put and compressed between said sealing struts of the two frame sections. Finally the invention consists of a process for the manufacture of a symmetrical profile provided with an internal square space for the construction of cabinets starting from a plane metal sheet, said process being characterized by the steps of: a) realizing a first bending of 90° in median position in order to form a dihedral which corner sets up the outer corner of the profile; b) bending each one of the two side sections of the dihedral at 90° in intermediate position and in the opposite direction of said first bending in order to form the two external side sections of the profile; c) bending each one of the end limbs of the folded metal sheet according to an angle of about 135° in the opposite direction with respect to the bendings of step b) in order to set up said first and second connecting portions, and d) completing said last bendings by a further angle of about 45° up to the overlapping of said internal side sections to said connecting portions. It will be evident to those skilled in the art that the particular shape of the symmetrical frame sections according to the invention makes it possible to obtain a double advantage inherent in the fact that it allows the use of a single type of hinge elements to assure the interchangeability of fixed and openable panels on all side sections of the cabinet, and in the fact that the moments of inertia with respect to the above-mentioned axes X and Y have the same value compared to the barycentre of the section, and therefore its parts are stressed in an uniform way even in case of flexure and torsional stress. Brief Description of the Drawings The feature of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by making reference to the following description taken together with the accompanying drawings, in which reference numerals identify the elements, and wherein: - Fig. 1 shows schematically the structure of a cabinet according to the invention; - Fig. 2 is a cross section illustrating the shape of the frame sections according to the invention - Fig. 3 is a perspective view showing the coupling of the frame sections with the walls, according to the invention; - Fig. 4 is a schematic cross section according to the line IV-IV of figure 6; - Fig. 5 shows the junction between a corner and the end of a frame section; - Fig. 6 is a partial view showing two frame sections and a corner of the cabinet according to the invention; - Fig. 7 is a perspective view showing a structure set up by two placed side by side and connected cabinets; - Fig. 7A shows the particular A of Fig. 7; - Fig. 8 is a partial view from above of the structure in Fig. 7; - Fig. 9 is a cross section according to line IX-IX in Fig. 7; - Fig. 9A shows the cross section of the gasket "at rest"; and - Fig 10A to 10E show the steps of the manufacture process of the frame sections. Detailed Description of the Preferred Embodiment Referring initially to Fig. 1 a cabinet according to the invention comprises a framework set up by frame sections connected at their ends and by a certain number of fixed and mobile panels or doors. More exactly in the embodiment shown in Fig. 1 the framework includes four vertical frame sections 1A, IB, 1C, ID, four lower horizontal frame sections 2A, 2B, 2C, 2D, and four upper horizontal frame sections 3A, 3B, 3C, 3D. The framework is closed by a bottom panel 4, a top panel 5, three fixed side panels 6, 7 and 8, and by a panel 9 provided with hinges 31 setting up an openable panel or door. The frame sections are connected in groups of three by angular blocks or corners 33 which construction will be shown in a more detailed way hereafter with reference to Fig. 5 and 6. The cross section of the frame sections or profile according to the invention is shown in Fig. 2. Said profile is set up by a metal sheet by means of folding and refolding. In the present description the term "folding" or "bending" is used to indicate a deformation of the metal sheet at about 90°, while the term "refolding" indicates a double bending or deformation which makes the sheet metal bend on itself by overlapping. Finally the term "beading" means a refolding of the sheet where the sheet metal lies on itself overlapping the double thickness of the refolded sheet in order to lock the folds together. For simplicity reasons the same reference will be used in the description to indicate either a bending (or refolding) or the relevant corner set up by this operation. Moreover a section is considered to be "open" when the ends edges of the single metal sheet it is set up by are "distant" and "closed" in the contrary case. Consequently an at one end overlapped profile obtained by beading is considered a closed one. When both ends substantially are mechanically not bound to each other, the section has to be defined as being "not closed". Therefore the profile of the present invention turns out being "not closed" and "without beading". Coming back to the profile of the present invention shown in Fig. 2 this is set up by a single folding and refolding metal sheet comprising: - a first external side section 13 and a second external side section 14 set up with the same length and externally connected by the external corner set up by a bending at 90° identified by reference numeral 15; - a first connecting portion 16 and a second connecting portion 17 with the same length and connected to said external side section 13 and 14 by means of two bendings at 90° identified by reference numerals 22 and 23; - a first internal side section 11 and a second internal side section 12 set up with the same length and being substantially perpendicularly arranged to each other. The ends edges of said first 16 and second 17 connecting portions together with the ends edges of said first 11 and second 12 internal side sections form portions of double thickness whose ends, identified by reference numerals 20 and 21, set up sealing struts which will be more clear with reference to Fig. 3. The external side sections 13 and 14 in combination with the portions 18 and 19 of the respective internal side sections 11 and 12 set up a substantially square space 10, or a channel with a square cross section extending for the whole profile. The profile according to the invention is therefore symmetrical with respect to the diagonal plane P passing through the intersection corner 15 of the planes containing the external side sections 13, 14. As better visible in Fig. 3 and 4, alternating holes with different diameters 24 and 27 on the portions 18 and 19 of the internal side sections are set up for the insertion and fastening of (not shown) internal elements like shelves and sections at a preset metrical pitch either by means of insertion of bushes or by the application of self-threading screws. Moreover in the external side sections 13 and 14 of the profile, holes are set up to receive blind threaded bushes 29. One of these bushes is shown (in cross section) in Fig. 4 and (visible) in Fig. 6. These bushes receive the ends of screws 28 for the fixing of panels on the profile passing through the panel and one of the external walls (see Fig. 3) . Thanks to this arrangement in case a screw is taken off or lost the tightness of the portions 18 and 19 is not endangered. Fig. 3 illustrates the connection modality of the parts which make up the cabinet according to the invention. As can be seen in the figure, panels 5 and 6 which are for example fixed on side section 1C are set up by metal sheets which are bent substantially at 90° along the edge to form two limbs 5A and 6A, respectively, with a minor length compared to the length of said connecting portions 16 and 17 of the profile. The panels are bound to the profile by means of the screws 28 or in case of mobile panels or doors by means of hinges 31. On the internal surface of the panels 4-8 and of the door 9 a gasket 32 of foamed elastomer material for example rubber is put which is compressed by the ends edge of one of side sections 20, 21 when the panel is fixed by means of screws 28 or - in case of the door - when this .one is closed, setting up said sealing struts. As it can be seen in Fig. 3, the tab 5A and the final part of panel 5 close nearly completely the flank with the exception of small interspaces 25 giving access to a first internal space (delimited by panel 6 and by the frame section), and through a second interspace 26 set up between the free edge 5A and the edge 15 to a second internal space (delimited by panel 5 and the frame section). The part of the profile according to the invention set up by the elements 13, 14, 16 and 17 (external portion of the profile) is without any openings and holes, and consequently the structure realizes an eave effect which interrupts the water jet and creates a difficult passage towards the interior and allows then the water to flow downwards. The profiles setting up the framework of the cabinet are connected by corner elements 33 shown in a more detailed way in Fig. 5 and 6. Each one of said couplings or corner elements 33 is set up as a block with a central body 34 of cubic shape from which three appendixes 35, 36 and 37 are extending with a square cross section and corresponding to the size of the square space 10 of the profile. The appendixes are inserted in the spaces of three frame sections then welded. Moreover body 34 provides for a threaded hole 38 into which the threaded end 41 of an eyebold (40) for the lifting of the cabinet or a lifting foot can be screwed (not shown) . According to the invention the body 33 of the block presents moreover a projecting part 39 on the face with the thread 38 for the eyebold or for a lifting foot. In this way it is avoided to put in a spacer between the roof or the upper panel 5 and the block or between the lower panel 4 and the block, a spacer which would be necessary to give the correct pressure to tighten the eyebold or the lifting foot. Fig. 7 shows in partial perspective a structure according to the invention set up by two cabinets which are placed side by side and bound together, one of them is for illustrative clearness reasons only partially shown. Fig. 7A shows a particularity indicated by box A of Fig. 7, while Fig. 9 is a cross section according to line IX-IX of Fig. 7 showing in a more detailed way the coupling of two cabinets. For the frame sections setting up one of the cabinets the same numerical references of Fig. 1 have been used while for the frame sections of the adjacent one the numerical references of corresponding parts are used but increased by 10. For the single elements of the profile the same symbols of Fig. 2 are used with the possible indication of the frame section (or of the cabinet) they belong to. Between the two profiles 1A and 11D placed side by side and belonging to the two adjacent cabinets, a flange 40 with an M-shaped cross section is put (see Fig. 9), which side sections or legs 41 and 42 are placed against the external side sections 13 and 14, respectively, of the symmetrical frame sections of two adjacent cabinets. On the side sections 41 and 42 of flange 40, holes 45 are foreseen through which screws 47 pass which engage in the blind threaded bushes 29 and bind the two cabinets together. A gasket 50 made of rubber or similar material is put and compressed between the edges 20 and 21 of the frame sections. The gasket 50, shown in its rest condition in Fig. 9A, has a cross section shape which is substantially rectangular with a slight tapering on the two boarders and provides for an internal tailrace 51 and two opposed side channels between which the ends edges 20 and 21 of the profiles are arranged in order to create a sealing strut. A similar arrangement is naturally foreseen between the upper horizontal side sections as illustrated in the partial view from above of Fig. 8 and between the other couples of either horizontal or vertical adjacent side sections. Fig. 10A to 10E show the steps of the process leading to the setting up of the symmetrical profile according to the invention. In the Figures, reference numerals are moreover progressively indicated in brackets which are assigned to the final portions of the frame section. Fig. 10A shows the original plane metal sheet identified by reference numeral 60. This sheet undergoes a first bending Pi at 90° in median position setting up the external edge 15 of the profile. The sheet takes therefore the dihedral configuration shown in Fig. 10B. Each one of the two side sections of the dihedral A and B undergoes a second bending at 90° indicated by P2A and P2B, respectively, in the direction opposed to the bending PI in order to set up the two external side sections 13 and 14 and the edges 22 and 23. The sheet gets the intermediate configuration with an overturned W-shaped cross section shown in Fig. IOC. Each one of the end limbs of the "W" thus undergoes a bending of about 135° indicated by P3A and P3B, respectively, in the direction opposed to that of the previous bendings P2A and P2B forming the portions 16 and 17. The sheet 60 get in this way a configuration similar to that of an M with divided and overturned summit as shown in Fig. 10D in which the side sections are the origin of the internal side portions 11 and 12. The bendings P3A and P3B are therefore carried on for a further 45° up to the overlapping of part of the bent side sections and in order to set up an angle of 90° between the edges of the internal side portions 11 and 12 which anyhow are not put together or beaded, considering that an airgap is formed between said internal side portions (Fig. 10E). The whole construction of the profile is realized by using a conventional machine like a so-called universal bending machine without the need of modifying the machine tooling. The invention achieves different and important advantages compared to the structures of the prior art. Using a piece of symmetrical (or specular) profile, a unique type of profile is necessary to construct all segments composing the framework. Moreover it turns out to be possible to apply doors even in side positions without modifications, and the cabinet is accessible from the bottom. Besides this, thanks to the symmetry of the profile according to the invention, a cabinet structure set up by it reacts in a homogeneous way to either static or dynamic torsion stress as the symmetry includes a constant moment of inertia. This improves the general reaction of the cabinet to potentially dangerous stresses like heavy loads, lifting of the cabinet etc. without deformations. According to the invention the frame sections are symmetrical and therefore realizable in a simple and economic way by means of conventional bending machines without the need of modifying the equipment. The junction of two or more cabinets requires only the presence of a simple M-shaped flange. Even the construction of the profile turns out to be simplified as it foresees a reduced number of bendings and refoldings, in particular seven, and being free of overlappings (beadings). Although the invention has been described referring in particular to a preferred embodiment it will be understood by those skilled in the art that various other modifications and changes may be made to the present invention without departing from the spirit and scope thereof.

Claims: CLAIMS 1. Sealed metallic cabinet, especially for electric and electronic equipment comprising a framework set up by twelve interconnected frame sections of the same profile on which external panels (4, 5, 6, 7, 8) and doors (9) are installed provided with sealing gaskets, the cross section of the frame sections comprising a first (13) and a second (14) external side sections which extend substantially in a perpendicular way to each other, and a first (11) and a second (12) internal side sections which extend substantially in a perpendicular way to each other, said first (13) and second (14) external side sections being connected to said first (11) and second (12) internal side sections by means of a first (16) and a second (17) connecting portions, the combination of said side sections (13, 14, 11, 12) setting up a square space (10) inside the frame sections, characterized in that: - said profile is symmetrical with respect to the diagonal plane (P) passing through the intersection angle of the plane containing said external side sections (13, 14); - the ends edges of said first (16) and second (17) connecting portions forming, in cooperation with the ends edges of a said first (11) and second (12) internal side, sealing struts able to engage said sealing gaskets (32) of said external panels (4, 5, 6, 7, 8) and door (9). 2. Sealed metallic cabinet according to claim 1, characterized in that said profile is realized by means of a single metal sheet with free ends edges of the sheet remaining substantially in an adjacent position but being not mechanically connected along the intersection corner of the planes containing said internal side sections (11, 12). 3. Sealed metallic cabinet according to claim 1 or 2, characterized in that on said external side sections (13, 14) of the profile holes are set up receiving blind threaded bushes (29) which apply to the ends of the screws (28) fixing the panels (4 - 8) at the frame sections. 4. Sealed metallic cabinet according to claim 3, characterized in that said panels (5, 6) are set up by metal sheets which are refolded substantially at 90° along the edges to set up limb portions (5A, 6A) . 5. Sealed metallic cabinet according to claim 3, characterized in that said door (9) is set up by a metal sheet refolded substantially at 90° along the edges to set up limb portions and fixed by means of hinges (31) to the frame work in correspondence to the external sides of the profile. 6. Sealed metallic cabinet according to claim 3 or 4, characterized in that it is provided in correspondence to the corners with an eave or labyrinth structure set up by contiguous panels, by their limb portions (5A, 6A) and by the frame sections on which said panels are installed. 7. Sealed metallic cabinet according to claim 6, characterized in that said labyrinth comprises a first passage (25) defined between the limb portions of a panel (5, 6) and of a panel or of an adjacent door (9), and a second passage (26) set up between the free edge (5A) of a panel or the external corner (15) formed by said first (13) and second (14) external side sections. 8. Sealed metallic cabinet according to the preceding claims, characterized in that the frame sections (1A, IB, 1C, ID, 2A, 2B, 2C, 2D, 3A, 3B, 3C, 3D) setting up the framework are connected by welded coupling elements (33). 9. Sealed metallic cabinet according to claim 8, characterized in that each one of said coupling elements or junction elements (33) is set up like a block with a central body (34) of a cubic shape from which three appendixes (35, 36 and 37) extend with a square section corresponding to the dimensions of said square space (10) of the profile. 10. Sealed metallic cabinet according to claim 9, characterized in that said central body (34) is provided with a threaded hole into which the threaded end (41) of an eyebold (40) for the lifting of the cabinet or a lifting foot can be screwed, and is provided furthermore with a projecting part (39) on the face with said threaded hole (38). 11. Sealed metallic cabinet according to the preceding claims, characterized in that on the portions (18, 19) of said internal side sections (11, 12) holes (24, 27) of different and alternating diameters are set up. 12. Structure, especially for electric and electronic equipment, comprising two or more metallic cabinets according to one of the preceding claims, which are arranged in an adjacent and connected way, characterized in that between two parallel and opposite frame sections (1A, 11D) belonging to two adjacent frameworks a flange (40) with an open M section is put, the legs (41, 42) of said flange (40) provided with holes (45) being abutted respectively on the external side sections (13, 14) of the symmetrical profiles of the two frame sections (1A, 11D), said flange (40) being fixed to blind threaded bushes (29) applied to said external side sections (13, 14) by means of screws passing through holes (45) of the flange, and further characterized in that a sealing gasket (50) is put and compressed between said sealing struts (20, 21) of the two frame sections (1A, 11D). 13. Structure according to claim 12, characterized in that said sealing gasket (50) has a substantially rectangular cross section with a slight tapering on two sides and foresees an internal tailrace (51) and two opposed side channels (52, 53) between which the said sealing struts (20, 21) are arranged. 14. Process for the manufacture of a symmetrical profile provided with an internal square space (10) for the construction of cabinets according to one of the claims from 1 to 11 starting from a plane metal sheet (60), said process being characterized by the steps of: a) realizing a first bending of 90° (Pi) in median position in order to form a dihedral which corner sets up the outer corner (15) of the profile; b) bending (P2A, P2B) each one of the two side sections of the dihedral at 90° in intermediate position and in the opposite direction of said first bending (Pi) in order to form the two external side sections (13, 14) of the profile (10); c) bending (P3A, P3B) each one of the end limbs of the folded metal sheet according to an angle of about 135° in the opposite direction with respect to the bendings (P2A, P2B) of step b) in order to set up said first (16) and second (17) connecting portions, and d) completing said last bendings (P3A, P3B) by a further angle of about 45° up to the overlapping of said internal side sections (11, 12) to said connecting portions (16, 17). 15. Process according to claim 14, characterized in that step d) is realized by pressing said internal side sections (12, 18) against said connecting portions (16, 17).

Inventors: MARTELLI ENZO, PUCCIARINI PAOLO, MARTELLI, ENZO, PUCCIARINI, PAOLO
Applicants: ITALTEL SPA, ITALTEL TECNOMECCANICA S.P.A.
Application year: 1994
Main classification: H05K7
IPC codes: H02B1, H05K7